callr                   Call R from R
poll                    Poll for process I/O or termination
process                 External process
r                       Evaluate an expression in another R session
r_bg                    Evaluate an expression in another R session, in
                        the background
r_copycat               Run an R process that mimics the current R
                        process
r_process               External R Process
r_process_options       Create options for an r_process object
r_vanilla               Run an R child process, with no configuration
rcmd                    Run an R CMD command
rcmd_bg                 Run an R CMD command in the background
rcmd_copycat            Call and R CMD command, while mimicking the
                        current R session
rcmd_process            External R CMD Process
rcmd_process_options    Create options for an rcmd_process object
rcmd_safe_env           'rcmd_safe_env' returns a set of environment
                        variables that are more appropriate for
                        'rcmd_safe()'. It is exported to allow
                        manipulating these variables (e.g. add an extra
                        one), before passing them to the 'rcmd()'
                        functions.
run                     Run external command, and wait until finishes
